Selective multi-link operation in a wireless local area network

ABSTRACT

This disclosure relates to methods for conducting multilink communications between a user equipment (UE) device and a remote device over a wireless local area network (WLAN). The UE device periodically transmits communications to the remote device over a first frequency band on the WLAN using a first radio. The UE device may determine to switch from transmitting communications to the remote device over the first frequency band to transmitting said communications over a second frequency band. The UE device then transmits communications to the remote device over the second frequency band on the WLAN.

PRIORITY CLAIM

This application is a divisional of U.S. patent application Ser. No.16/890,031, titled “Selective Multi-link Operation in a Wireless LocalArea Network” and filed on Jun. 2, 2020, which claims priority to U.S.Provisional Patent Application No. 62/956,429, titled “SelectiveMulti-link Operation in a Wireless Local Area Network” and filed on Jan.2, 2020, both of which are hereby incorporated by reference in theirentirety, as though fully and completely set forth herein.

The claims in the instant application are different than those of theparent application and/or other related applications. The Applicanttherefore rescinds any disclaimer of claim scope made in the parentapplication and/or any predecessor application in relation to theinstant application. Any such previous disclaimer and the citedreferences that it was made to avoid, may need to be revisited. Further,any disclaimer made in the instant application should not be read intoor against the parent application and/or other related applications.

TECHNICAL FIELD

The present application relates to wireless communication, includingtechniques and devices for improved performance of a user equipmentdevice in a multi-link wireless local area network architecture.

DESCRIPTION OF THE RELATED ART

Wireless communication systems are rapidly growing in usage. Further,wireless communication technology has evolved from voice-onlycommunications to also include the transmission of data, such asInternet and multimedia content.

Mobile electronic devices, or user equipment devices (UEs) may take theform of smart phones or tablets that a user typically carries.Additionally, UEs may be configured to simultaneously communicate overmultiple wireless links over a wireless local area network (WLAN). Theavailability of multiple WLAN links may offer a potential for increasedthroughput and latency reduction. However, avoiding traffic collisionsand congestion may be more difficult in a multiple link environment.Accordingly, improvements in the field are desired.

SUMMARY

Embodiments are presented herein of, inter alia, systems, apparatuses,and methods for devices for improved performance of a user equipmentdevice in a multi-link wireless local area network (WLAN) environment.

A user equipment device (UE) may comprise one or more antennas, one ormore radios operably coupled to the one or more antennas, and aprocessor operably coupled to the one or more radios.

In some embodiments, the UE may exchange capability information with aremote device over a primary frequency band of a wireless local areanetwork (WLAN). The UE may exchange signaling to set up selectivetransmission over the WLAN. The UE may transmit a notification to theremote device to initiate selective transmission over an alternativefrequency band. In some embodiments, transmitting the notification tothe remote device to initiate selective transmission over thealternative frequency band may be performed in response to determiningthat a frame associated with the first frequency band has been reservedfor longer than a threshold duration of time

In some embodiments, the UE may then transmit one or more messages tothe remote device over the alternative frequency band. In someembodiments, said transmitting the one or more messages over thealternative frequency band may be performed until a remaining durationof time that the frame is reserved is less than the threshold durationof time.

The techniques described herein may be implemented in and/or used with anumber of different types of devices, including but not limited tocellular phones, tablet computers, accessory and/or wearable computingdevices, portable media players, cellular base stations and othercellular network infrastructure equipment, servers, and any of variousother computing devices.

This summary is intended to provide a brief overview of some of thesubject matter described in this document. Accordingly, it will beappreciated that the above-described features are merely examples andshould not be construed to narrow the scope or spirit of the subjectmatter described herein in any way. Other features, aspects, andadvantages of the subject matter described herein will become apparentfrom the following Detailed Description, Figures, and Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present subject matter can be obtainedwhen the following detailed description of the embodiments is consideredin conjunction with the following drawings.

FIG. 1 illustrates an example wireless communication system including auser equipment device (UE), according to some embodiments;

FIG. 2 is a block diagram illustrating an example UE, according to someembodiments;

FIG. 3 is a block diagram illustrating an example wireless access point,according to some embodiments;

FIG. 4 is a flowchart diagram illustrating a method for implementingselective transmission (S-Tx) over a wireless local area network usingmultiple links, according to some embodiments;

FIG. 5 is a flowchart diagram illustrating a method for switching afrequency band for wireless transmissions based on reservation time,according to some embodiments;

FIG. 6 illustrates scheduling of target wakeup times (TWTs) for atransmitter device and a receiver device implementing a S-Tx mode,according to some embodiments;

FIG. 7 illustrates an implementation of single-radio S-Tx mode by areceiver device, according to some embodiments;

FIG. 8 is an example of bit field allocation for the 802.11be standard,according to some embodiments;

FIG. 9 is a schematic diagram illustrating a situation where latepackets arrive during a low-latency traffic transmission, according tosome embodiments;

FIG. 10 is a schematic diagram illustrating a method for mitigating latepacket transmissions during a low-latency traffic transmission,according to some embodiments; and

FIG. 11 is a flowchart diagram illustrating a method for mitigating latepacket transmissions, according to some embodiments.

While the features described herein are susceptible to variousmodifications and alternative forms, specific embodiments thereof areshown by way of example in the drawings and are herein described indetail. It should be understood, however, that the drawings and detaileddescription thereto are not intended to be limiting to the particularform disclosed, but on the contrary, the intention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the subject matter as defined by the appended claims.

DETAILED DESCRIPTION Terminology

The following are definitions of terms used in this disclosure:

Memory Medium—Any of various types of non-transitory memory devices orstorage devices. The term “memory medium” is intended to include aninstallation medium, e.g., a CD-ROM, floppy disks, or tape device; acomputer system memory or random access memory such as DRAM, DDR RAM,SRAM, EDO RAM, Rambus RAM, etc.; a non-volatile memory such as a Flash,magnetic media, e.g., a hard drive, or optical storage; registers, orother similar types of memory elements, etc. The memory medium mayinclude other types of non-transitory memory as well or combinationsthereof. In addition, the memory medium may be located in a firstcomputer system in which the programs are executed, or may be located ina second different computer system which connects to the first computersystem over a network, such as the Internet. In the latter instance, thesecond computer system may provide program instructions to the firstcomputer for execution. The term “memory medium” may include two or morememory mediums which may reside in different locations, e.g., indifferent computer systems that are connected over a network. The memorymedium may store program instructions (e.g., embodied as computerprograms) that may be executed by one or more processors.

Carrier Medium—a memory medium as described above, as well as a physicaltransmission medium, such as a bus, network, and/or other physicaltransmission medium that conveys signals such as electrical,electromagnetic, or digital signals.

Programmable Hardware Element—includes various hardware devicescomprising multiple programmable function blocks connected via aprogrammable interconnect. Examples include FPGAs (Field ProgrammableGate Arrays), PLDs (Programmable Logic Devices), FPOAs (FieldProgrammable Object Arrays), and CPLDs (Complex PLDs). The programmablefunction blocks may range from fine grained (combinatorial logic or lookup tables) to coarse grained (arithmetic logic units or processorcores). A programmable hardware element may also be referred to as“reconfigurable logic”.

Computer System—any of various types of computing or processing systems,including a personal computer system (PC), mainframe computer system,workstation, network appliance, Internet appliance, personal digitalassistant (PDA), television system, grid computing system, or otherdevice or combinations of devices. In general, the term “computersystem” can be broadly defined to encompass any device (or combinationof devices) having at least one processor that executes instructionsfrom a memory medium.

User Equipment (UE) (or “UE Device”)—any of various types of computersystems devices which are mobile or portable and which performs wirelesscommunications. Examples of UE devices include mobile telephones orsmart phones (e.g., iPhone™, Android™-based phones), portable gamingdevices (e.g., Nintendo DS™, PlayStation Portable™, Gameboy Advance™,iPhone™), laptops, wearable devices (e.g. smart watch, smart glasses),PDAs, portable Internet devices, music players, data storage devices, orother handheld devices, etc. In general, the term “UE” or “UE device”can be broadly defined to encompass any electronic, computing, and/ortelecommunications device (or combination of devices) which is easilytransported by a user and capable of wireless communication.

Wireless Device—any of various types of computer system devices whichperforms wireless communications. A wireless device can be portable (ormobile) or may be stationary or fixed at a certain location. A UE is anexample of a wireless device.

Communication Device—any of various types of computer systems or devicesthat perform communications, where the communications can be wired orwireless. A communication device can be portable (or mobile) or may bestationary or fixed at a certain location. A wireless device is anexample of a communication device. A UE is another example of acommunication device.

Base Station—The term “Base Station” (also called “eNB”) has the fullbreadth of its ordinary meaning, and at least includes a wirelesscommunication station installed at a fixed location and used tocommunicate as part of a wireless cellular communication system.

Link Budget Limited—includes the full breadth of its ordinary meaning,and at least includes a characteristic of a wireless device (a UE) whichexhibits limited communication capabilities, or limited power, relativeto a device that is not link budget limited, or relative to devices forwhich a radio access technology (RAT) standard has been developed. A UEthat is link budget limited may experience relatively limited receptionand/or transmission capabilities, which may be due to one or morefactors such as device design, device size, battery size, antenna sizeor design, transmit power, receive power, current transmission mediumconditions, and/or other factors. Such devices may be referred to hereinas “link budget limited” (or “link budget constrained”) devices. Adevice may be inherently link budget limited due to its size, batterypower, and/or transmit/receive power. For example, a smart watch that iscommunicating over LTE or LTE-A with a base station may be inherentlylink budget limited due to its reduced transmit/receive power and/orreduced antenna. Wearable devices, such as smart watches, are generallylink budget limited devices. Alternatively, a device may not beinherently link budget limited, e.g., may have sufficient size, batterypower, and/or transmit/receive power for normal communications over LTEor LTE-A, but may be temporarily link budget limited due to currentcommunication conditions, e.g., a smart phone being at the edge of acell, etc. It is noted that the term “link budget limited” includes orencompasses power limitations, and thus a power limited device may beconsidered a link budget limited device.

Processing Element—refers to various elements or combinations ofelements. Processing elements include, for example, circuits such as anASIC (Application Specific Integrated Circuit), portions or circuits ofindividual processor cores, entire processor cores, individualprocessors, programmable hardware devices such as a field programmablegate array (FPGA), and/or larger portions of systems that includemultiple processors.

Automatically—refers to an action or operation performed by a computersystem (e.g., software executed by the computer system) or device (e.g.,circuitry, programmable hardware elements, ASICs, etc.), without userinput directly specifying or performing the action or operation. Thusthe term “automatically” is in contrast to an operation being manuallyperformed or specified by the user, where the user provides input todirectly perform the operation. An automatic procedure may be initiatedby input provided by the user, but the subsequent actions that areperformed “automatically” are not specified by the user, i.e., are notperformed “manually”, where the user specifies each action to perform.For example, a user filling out an electronic form by selecting eachfield and providing input specifying information (e.g., by typinginformation, selecting check boxes, radio selections, etc.) is fillingout the form manually, even though the computer system must update theform in response to the user actions. The form may be automaticallyfilled out by the computer system where the computer system (e.g.,software executing on the computer system) analyzes the fields of theform and fills in the form without any user input specifying the answersto the fields. As indicated above, the user may invoke the automaticfilling of the form, but is not involved in the actual filling of theform (e.g., the user is not manually specifying answers to fields butrather they are being automatically completed). The presentspecification provides various examples of operations beingautomatically performed in response to actions the user has taken.

Configured to—Various components may be described as “configured to”perform a task or tasks. In such contexts, “configured to” is a broadrecitation generally meaning “having structure that” performs the taskor tasks during operation. As such, the component can be configured toperform the task even when the component is not currently performingthat task (e.g., a set of electrical conductors may be configured toelectrically connect a module to another module, even when the twomodules are not connected). In some contexts, “configured to” may be abroad recitation of structure generally meaning “having circuitry that”performs the task or tasks during operation. As such, the component canbe configured to perform the task even when the component is notcurrently on. In general, the circuitry that forms the structurecorresponding to “configured to” may include hardware circuits.

Various components may be described as performing a task or tasks, forconvenience in the description. Such descriptions should be interpretedas including the phrase “configured to.” Reciting a component that isconfigured to perform one or more tasks is expressly intended not toinvoke 35 U.S.C. § 112, paragraph six, interpretation for thatcomponent.

FIGS. 1-2—Wireless Communication System

FIG. 1 illustrates an example of a wireless cellular communicationsystem. It is noted that FIG. 1 represents one possibility among many,and that features of the present disclosure may be implemented in any ofvarious systems, as desired. For example, embodiments described hereinmay be implemented in any type of wireless device. The wirelessembodiment described below is one example embodiment.

As shown, the exemplary wireless communication system includes acellular base station 102, which communicates over a transmission mediumwith one or more wireless devices 106A, 106B, etc. Wireless devices 106Aand 106B may be user devices, which may be referred to herein as “userequipment” (UE), UEs, or UE devices.

The base station 102 may be a base transceiver station (BTS) or cellsite, and may include hardware that enables wireless communication withthe UE devices 106A and 106B. The base station 102 may also be equippedto communicate with a network 100 (e.g., a core network of a cellularservice provider, a telecommunication network such as a public switchedtelephone network (PSTN), and/or the Internet, among variouspossibilities). Thus, the base station 102 may facilitate communicationamong the UE devices 106 and/or between the UE devices 106 and thenetwork 100. In other implementations, base station 102 can beconfigured to provide communications over one or more other wirelesstechnologies, such as an access point supporting one or more WLANprotocols, such as 802.11 a, b, g, n, ac, ad, ay, be and/or ax, or LTEin an unlicensed band (LAA).

The communication area (or coverage area) of the base station 102 may bereferred to as a “cell.” The base station 102 and the UEs 106 may beconfigured to communicate over the transmission medium using any ofvarious radio access technologies (RATs) or wireless communicationtechnologies, such as GSM, UMTS (WCDMA, TDS-CDMA), LTE, LTE-Advanced(LTE-A), 5G NR, HSPA, 3GPP2 CDMA2000 (e.g., 1×RTT, 1×EV-DO, HRPD,eHRPD), Wi-Fi, WiMAX etc.

Base station 102 and other similar base stations (not shown) operatingaccording to one or more cellular communication technologies may thus beprovided as a network of cells, which may provide continuous or nearlycontinuous overlapping service to UE devices 106A-N and similar devicesover a geographic area via one or more cellular communicationtechnologies.

Note that at least in some instances a UE device 106 may be capable ofcommunicating using any of a plurality of wireless communicationtechnologies. For example, a UE device 106 might be configured tocommunicate using one or more of GSM, UMTS, CDMA2000, LTE, LTE-A, 5G NR,WLAN, WiFi, Bluetooth™, one or more global navigational satellitesystems (GNSS, e.g., GPS or GLONASS), one and/or more mobile televisionbroadcasting standards (e.g., ATSC-M/H), etc. Other combinations ofwireless communication technologies (including more than two wirelesscommunication technologies) are also possible. Likewise, in someinstances a UE device 106 may be configured to communicate using only asingle wireless communication technology.

As shown, the exemplary wireless communication system also includes aWLAN access point (AP) 104, which communicates over a transmissionmedium with the wireless device 106B. The WLAN access point, which maybe a Wi-Fi AP, also provides communicative connectivity to the network100. Thus, according to some embodiments, wireless devices may be ableto connect to either or both of the base station 102 (or anothercellular base station) and the access point 104 (or another accesspoint) to access the network 100 at a given time.

The UEs 106A and 106B may include handheld devices such as smart phonesor tablets, and/or may include any of various types of device withcellular communications capability. For example, one or more of the UEs106A and 106B may be a wireless device intended for stationary ornomadic deployment such as an appliance, measurement device, controldevice, etc.

The UE 106B may also be configured to communicate with the UE 106A. Forexample, the UE 106A and UE 106B may be capable of performing directdevice-to-device (D2D) communication. The D2D communication may besupported by the cellular base station 102 (e.g., the BS 102 mayfacilitate discovery, among various possible forms of assistance), ormay be performed in a manner unsupported by the BS 102.

The UE 106 may include a device or integrated circuit for facilitatingcellular communication, referred to as a cellular modem. The cellularmodem may include one or more processors (processor elements) andvarious hardware components as described herein. The UE 106 may performany of the method embodiments described herein by executing instructionson one or more programmable processors. Alternatively, or in addition,the one or more processors may be one or more programmable hardwareelements such as an FPGA (field-programmable gate array), or othercircuitry, that is configured to perform any of the method embodimentsdescribed herein, or any portion of any of the method embodimentsdescribed herein. The cellular modem described herein may be used in aUE device as defined herein, a wireless device as defined herein, or acommunication device as defined herein. The cellular modem describedherein may also be used in a base station or other similar network sidedevice.

The UE 106 may include one or more antennas for communicating using twoor more wireless communication protocols or radio access technologies.In some embodiments, the UE device 106 might be configured tocommunicate using a single shared radio. The shared radio may couple toa single antenna, or may couple to multiple antennas (e.g., for MIMO)for performing wireless communications. Alternatively, the UE device 106may include two or more radios, each of which may be configured tocommunicate via a respective wireless link. Other configurations arealso possible.

FIG. 2—Example Block Diagram of a UE Device

FIG. 2 illustrates one possible block diagram of an UE device, such asUE device 106. As shown, the UE device 106 may include a system on chip(SOC) 300, which may include portions for various purposes. For example,as shown, the SOC 300 may include processor(s) 302 which may executeprogram instructions for the UE device 106, and display circuitry 304which may perform graphics processing and provide display signals to thedisplay 360. The SOC 300 may also include motion sensing circuitry 370which may detect motion of the UE 106, for example using a gyroscope,accelerometer, and/or any of various other motion sensing components.The processor(s) 302 may also be coupled to memory management unit (MMU)340, which may be configured to receive addresses from the processor(s)302 and translate those addresses to locations in memory (e.g., memory306, read only memory (ROM) 350, flash memory 310). The MMU 340 may beconfigured to perform memory protection and page table translation orset up. In some embodiments, the MMU 340 may be included as a portion ofthe processor(s) 302.

As shown, the SOC 300 may be coupled to various other circuits of the UE106. For example, the UE 106 may include various types of memory (e.g.,including NAND flash 310), a connector interface 320 (e.g., for couplingto a computer system, dock, charging station, etc.), the display 360,and wireless communication circuitry 330 (e.g., for LTE, LTE-A, NR,CDMA2000, BlueTooth™, Wi-Fi, NFC, GPS, etc.).

The UE device 106 may include at least one antenna, and in someembodiments multiple antennas 335 a and 335 b, for performing wirelesscommunication with base stations and/or other devices. For example, theUE device 106 may use antennas 335 a and 335 b to perform the wirelesscommunication. As noted above, the UE device 106 may in some embodimentsbe configured to communicate wirelessly using a plurality of wirelesscommunication standards or radio access technologies (RATs).

The wireless communication circuitry 330 may include Wi-Fi Logic 332, aCellular Modem 334, and BlueTooth™ Logic 336. The Wi-Fi Logic 332 is forenabling the UE device 106 to perform Wi-Fi or other WLAN communicationson an 802.11 network. The BlueTooth™ Logic 336 is for enabling the UEdevice 106 to perform BlueTooth™ communications. The cellular modem 334may be a cellular modem capable of performing cellular communicationaccording to one or more cellular communication technologies.

As described herein, UE 106 may include hardware and software componentsfor implementing embodiments of this disclosure. For example, one ormore components of the wireless communication circuitry 330 (e.g., Wi-Filogic 332, cellular modem 334, BT logic 336) of the UE device 106 may beconfigured to implement part or all of the methods described herein,e.g., by a processor executing program instructions stored on a memorymedium (e.g., a non-transitory computer-readable memory medium), aprocessor configured as an FPGA (Field Programmable Gate Array), and/orusing dedicated hardware components, which may include an ASIC(Application Specific Integrated Circuit).

FIG. 3—Block Diagram of an Access Point

FIG. 3 illustrates an example block diagram of an access point (AP) 104,according to some embodiments. It is noted that the AP of FIG. 3 ismerely one example of a possible access point. As shown, AP 104 mayinclude processor(s) 404 which may execute program instructions for theAP 104. The processor(s) 404 may also be coupled to memory managementunit (MMU) 440, which may be configured to receive addresses from theprocessor(s) 404 and translate those addresses to locations in memory(e.g., memory 460 and read only memory (ROM) 450) or to other circuitsor devices.

The AP 104 may include at least one network port 470. The network port470 may be configured to couple to a telephone network and provide aplurality of devices, such as UE devices 106, access to the telephonenetwork as described above in FIG. 1 .

The network port 470 (or an additional network port) may also oralternatively be configured to couple to a cellular network, e.g., acore network of a cellular service provider. The core network mayprovide mobility related services and/or other services to a pluralityof devices, such as UE devices 106. In some cases, the network port 470may couple to a telephone network via the core network, and/or the corenetwork may provide a telephone network (e.g., among other UE devicesserviced by the cellular service provider).

The AP 104 may include one or more radios 430A-430N, each of which maybe coupled to a respective communication chain and at least one antenna434, and possibly multiple antennas. The antenna(s) 434 may beconfigured to operate as a wireless transceiver and may be furtherconfigured to communicate with UE devices 106/107 via radio 430. Theantenna(s) 434A-N communicate with their respective radios 430A-N viacommunication chains 432A-N. Communication chains 432 may be receivechains, transmit chains, or both. The radios 430A-N may be configured tocommunicate via various wireless communication standards, including, butnot limited to, LTE, LTE-A, NR, GSM, UMTS, CDMA2000, Wi-Fi, etc. The UE106 may be configured to operate in multiple wireless links using theone or more radios 430A-N, wherein each radio is used to operate in arespective wireless link.

The AP 104 may be configured to communicate wirelessly using multiplewireless communication standards. In some instances, the base station102 may include multiple radios, which may enable the network entity tocommunicate according to multiple wireless communication technologies.For example, as one possibility, the AP 104 may include an LTE or 5G NRradio for performing communication according to LTE as well as a Wi-Firadio for performing communication according to Wi-Fi. In such a case,the AP 104 may be capable of operating as both an LTE base station and aWi-Fi access point. As another possibility, the AP 104 may include amulti-mode radio which is capable of performing communications accordingto any of multiple wireless communication technologies (e.g., NR andWi-Fi, NR and UMTS, LTE and CDMA2000, UMTS and GSM, etc.). As stillanother possibility, the AP 104 may be configured to act exclusively asa Wi-Fi access point, e.g., without cellular communication capability.

As described further subsequently herein, the AP 104 may includehardware and software components for implementing or supportingimplementation of features described herein. The processor 404 of theaccess point 104 may be configured to implement or supportimplementation of part or all of the methods described herein, e.g., byexecuting program instructions stored on a memory medium (e.g., anon-transitory computer-readable memory medium) to operate multiplewireless links using multiple respective radios. Alternatively, theprocessor 404 may be configured as a programmable hardware element, suchas an FPGA (Field Programmable Gate Array), or as an ASIC (ApplicationSpecific Integrated Circuit), or a combination thereof. Alternatively(or in addition) the processor 404 of the AP 104, in conjunction withone or more of the other components 430, 432, 434, 440, 450, 460, 470may be configured to implement or support implementation of part or allof the features described herein.

WLAN Communication Over Multiple Wireless Links

It is anticipated that upcoming implementations of wireless local areanetworks (WLANs) may utilize multiple links during communicationsbetween two wireless stations (STAs), e.g., two UEs 106 illustrated inFIG. 2 , or between a wireless STA and a wireless access point (AP) suchas the AP 104 illustrated in FIG. 3 , in either or both of uplink anddownlink communications. The STA may be any of a variety of types ofwireless stations, including but not limited to a UE 106, a smart phone,tablet, personal computer, smart watch, accessory device, or any othertype of wireless device capable of communicating over a WLAN.

The 802.11ax standard allows STAs and APs to communicate according toeither a 5 GHz link or a 2.4 GHz link, and it is anticipated that802.11.be may allow STAs and APs to communicate over a 6 GHz link inaddition to the 2.4 GHz and 5 GHz, to improve throughput and reducecommunication latency. In general, a higher frequency link may bepreferred as a default link for communications due to the higherthroughput, and one or more lower frequency links may be utilized asbackup to reduce latency and increase overall throughput. Embodimentsherein propose methods and devices for selective multi-link operation inthese and other communication environments.

In some current implementations of a wireless local area network (WLAN),a WLAN-capable device such as a UE device 106 may pause its backofftimer and/or new transmission attempts if it determines that the WLANmedium (e.g., a particular bandwidth used for WLAN communications, suchas 5 GHz or 2.4 GHz) is currently in use by another device. The UE mayresume the backoff timer and new transmission attempts only after thenetwork allocation vector (NAV) time, which may be specified in the MACheader field or duration field, expires. The maximum duration for whicha device is allowed to reserve the WLAN medium may be set to a maximumduration (such as around 32 ms, in some implementations), and thespecific duration of a WLAN medium reservation may be specified by theNAV.

In some embodiments, when a device sets a NAV duration in its packet, itmay block the medium for the entire NAV duration and all other devicesmay have to wait to initiate any new packet transmissions. Long NAVreservations near the maximum allowable duration of 32 ms have beenutilized in some WiFi devices for various reasons such as channelmeasurement, radio frequency (RF) tuning, etc. However, long NAVdurations may impair the user experience for some latency-sensitiveapplications such as audio stereo pairing which have a latencyrequirement in the range of 10 ms. In this example, an audio packet mayhave to wait for a long NAV to expire and in doing so it may exceed thelatency requirement of the audio service, leading to audio glitches anda poor user experience. In addition to NAV reservation, in congestedenvironments the channel may be otherwise occupied by other devices forsufficiently long durations of time to prevent a low latency device fromtransmitting in time to satisfy its latency requirements.

Some WLAN devices may have dual-band radios (e.g., 2.4 GHz and 5 GHz) oreven tri-band (2.4/5/6 GHz). In some embodiments, this multi-radiocapability may be utilized to mitigate the latency problems describedabove. As used herein, a “link” is defined as a communication channel ona particular frequency band for performing WLAN communications.Accordingly, “multi-link” communications refer to a transmitter andreceiver using multiple bands concurrently or selectively. Furthermore,the “resident band” may refer to the primary band used forcommunications, while the “alternative band” may refer to the backupband used for communications.

In some embodiments, for low latency applications over a WLAN, it may bedesirable for the transmitter to deliver the packets to the receiverwithin a strict allotted time budget, such as 20 msec or anotherduration. Delayed packets that are received outside of the allotted timebudget may be considered stale and may be dropped, adversely impactingthe quality of service intended for the specific application andpotentially causing an undesirable user experience.

In some embodiments, before a UE may transmit over a WLAN medium, it mayhave to wait for any ongoing network allocation vector (NAV) reservationto expire, upon which the UE may contend for access to the medium. Alonger duration NAV reservation by another device in the medium maypotentially delay the transmission of the packet and cause late arrivalat the receiver. The maximum NAV reservation currently allowed under the802.11 specification is 32.767 milliseconds. As noted above, if aneighboring device reserves the WLAN medium for this duration, it mayimpact the latency budget set for a particular application (e.g., forlow latency applications with a 20 msec latency requirement, as oneexample). In some embodiments, WLAN devices may reserve the medium bytransmitting a clear-to-send (e.g., CTS2Self) frame with a set duration(e.g., up to 32.767 milliseconds for the 802.11 specification) for anumber of reasons, including muting transmissions from connected peerdevices for performing off-channel activity, BTCoex (BlueTooth™coexistence), PHY (physical layer) calibrations, or other reasons. Insome embodiments, to mitigate against the channel unavailability duringundesirably long NAV reservation and also to achieve the targetedlatency budget, transmitters and/or receivers may utilize theirsecondary radio during undesirably long NAV reservations.

Embodiments herein describe various methodologies for utilizing multipleradio capabilities in a WLAN-capable device to switch to different bandsfor transmitting and/or receiving WLAN communications under certaintrigger conditions. Selectively switching the frequency band fortransmitting WLAN communications may be referred to herein as “selectivetransmission”, (S-Tx). According to various embodiments, switchingbetween bands may operate according to one of five modes, among otherpossibilities, which are briefly summarized here and described ingreater detail under separate section headings below.

In a first set of embodiments (“Mode 1”), a UE may operate according toan independent selective mode, which may not rely on any signalingbetween transmitter (Tx) and receiver (Rx) devices, whereby the Txdevice autonomously/automatically switches between bands based on itsown criteria and/or conditions

In a second set of embodiments (“Mode 2”), a UE may operate according toa basic collaborative selective mode, whereby the Tx device and Rxdevice exchange critical information to configure how and/or when theband switch may occur. Mode 2 operation may assume that the Rx is awake100% of the time on all of the available bands.

In a third set of embodiments (“Mode 3”), a UE may operate according toa non-scheduled power-save selective Tx mode. In these embodiments, theRx device may be asleep on the alternative band most of the time and maybe awoken in the alternative band by out-of-band signaling when thechannel switch is about to happen at the Tx side.

In a fourth set of embodiments, (“Mode 4”), a UE may operate accordingto a scheduled power-save selective Tx mode. In these embodiments, theRx device and Tx device may agree on a particular time window for the Txdevice to sleep on each of the resident and alternative bands. The Txdevice may switch bands to transmit packets during the time window thatcorresponds to each particular band.

In a fifth set of embodiments (“Mode 5”), a UE may operate according toselective transmission for a single radio device, whereby the Rx devicedoes not have multiple radio capabilities, and the Tx device and Rxdevice agree on the switching condition and/or time to keep synchronizedon the operating band.

Each of these modes and their corresponding signaling mechanisms areexplained in greater detail below.

FIG. 4—Flowchart for Selective Band Transmission

FIG. 4 is a flowchart diagram illustrating a method for conducting aband switch in WLAN communications, according to some embodiments. Themethod steps described in FIG. 4 may be performed consistently with anyof Modes 1-5 described herein, although, as described in greater detailbelow, the separate modes may differ in their specific implementation ofthe method steps. In other words, the method steps of FIG. 4 provide ahigh-level description of a method for conducting a band switch in WLANcommunications, while each of Modes 1-5 provide additional specificimplementation details, according to various embodiments. The methodshown in FIG. 4 may be used in conjunction with any of the computersystems or devices shown in the above Figures, among other devices. Themethod may be implemented by a processor of the UE, such as theprocessor(s) 302 illustrated in FIG. 3 , which may execute programinstructions to cause the UE to implement the described method steps. Invarious embodiments, some of the elements of the methods shown may beperformed concurrently, in a different order than shown, may besubstituted for by other method elements, or may be omitted. Additionalmethod elements may also be performed as desired. As shown, the methodmay operate as follows.

At 402, a capability exchange is performed on the resident band. Thecapability exchange may be utilized to allow each of the Rx and Txdevices to determine the appropriate mode to use for S-Tx operation. Forexample, the capability exchange may be utilized for each of the Rx andTx devices to determine which frequency bands and/or channels the otherdevice is configured to communicate on, whether the other device iscapable of simultaneous dual-band communications, band switch latency,or to determine other capability information.

At 404, the signaling parameters of the S-Tx may be set up between theTx device and the Rx device. In various embodiments, the signalingparameters may include one or more of timing and/or duration of bandswitching, trigger conditions for switching, or other parameters relatedto S-Tx operation, as described in greater detail below. In someembodiments, the Tx and Rx devices may exchange signaling to establishsignaling parameters for implementing S-Tx. Alternatively, in someembodiments the Tx device may autonomously set up the signalingparameters.

At 406, a notification may be sent that Tx on the alternative band isinitiated. In some embodiments, a low power radio such as BlueTooth™ LowEnergy (BLE) may (optionally) be used as a wake-up radio to dynamicallyactivate remote band operation.

At 408, packet transmissions may be performed on the alternative band.In other words, the Tx device may transmit packets to the Rx device onthe alternative band.

At 410 (optional), the Tx device may switch back to the resident bandfor performing transmissions. In various embodiments, switching back tothe resident band may be performed based on expiration of a timer, orbecause of a trigger condition, among other possibilities.

The following sections give additional description related to how eachof Modes 1-5 may be used to implement steps 402-410 of FIG. 4 .

Mode 1: Independent Band Selection

For Mode 1 operation, it may be assumed that the Rx device is awake onboth the resident and alternative bands (e.g., the 5 GHz and the 2.4 GHzbands). In some embodiments, both the Tx device and the Rx device arecapable of simultaneous dual-band (or potentially tri-band) radiocommunications.

For step 402, the Tx device and the Rx device may set up a one blockacknowledgment (ACK) session on one of the bands, and this block ACKsession may be shared between both bands. Note that in typical Wi-Fioperation, each radio may have separate block ACK sessions which maymaintain separate sequence numbers and ACK bitmaps for packets sent ondifferent bands.

For step 404, S-Tx may be autonomously/automatically set up on the Txside. More specifically, the Tx device may set up a latency timer ofduration T1 as the channel switching condition. The Tx device may set upa resident band, which may be performed without informing the Rx devicesince the Rx device may be available on both bands and may use the sameblock ACK session on both bands. In other words, the Rx device may beconfigured to receive and acknowledge messages from the Tx device oneither of the resident and alternative band, such that the Tx device mayset up a first band as the resident band without coordinating with theRx device.

For step 406, when the Tx device determines that the channel reservationvalue (e.g., the NAV) on current band is larger than T1, it may switchthe transmission to the alternative band and check the NAV value on thealternative band. Subsequently, the Tx device may select the band whichhas the smaller NAV for transmission. When using three bands, it may usethe band having the shortest current NAV among the three possibilities.As another possibility, the Tx device may only switch to a new band ifthe new band is below a NAV threshold (e.g., T1), but may remain on theresident band otherwise.

For step 408, the Tx device may transmit one or both of arequest-to-send (RTS) or clear-to-send (CTS) protocol on the alternateband before the actual packet transmission, to verify that the Rx deviceis available to receive.

For step 410, if the packet is successfully transmitted on thealternative band, the Tx device may switch back to using the residentband. Alternatively, the Tx device may switch back to the resident bandif it has reached the retry limit or reached another time threshold. Insome embodiments, the Tx device may only switch back to the residentband if the current NAV of the resident band is less than a threshold.Additionally, or alternatively, the Tx device may track historicalinformation for each band and may use that historical information indetermining when to switch between bands. For example, if the Tx devicehas determined that the resident band is consistently being used forlong NAVs, it may prefer the alternative band(s) until the resident bandis more available. The same behavior can be used in choosing amongalternative band(s) and/or determining when to switch back to theresident band.

FIG. 5—Flowchart for Mode 1

FIG. 5 is a flowchart diagram illustrating method steps specific to Mode1 operation for S-Tx implementations, according to some embodiments. Themethod steps of FIG. 5 may be performed by a UE such as the UEs 106A-Billustrated in FIGS. 1-2 , for example. In some embodiments, the methodsteps may be performed by a processor operably coupled to a first andsecond radio. In some embodiments, the first radio is configured toperform wireless communications over a first frequency band or channelon a wireless local area network (WLAN), and the second radio isconfigured to perform wireless communications over a second frequencyband or channel on the WLAN. In some embodiments, the first frequencyband is a 5 GHz frequency band which serves as a primary or residentband, while the second frequency band is a 2.4 GHz frequency band thatserves as a secondary or auxiliary band. Alternatively, each of thefirst and second frequency bands may be any of a 2.4 GHz, 5 GHz, 6 GHzband, or another frequency band.

In some embodiments, the method steps shown may be performed between aUE and a remote device, which may be another UE of the same or adifferent type. The communications between the two devices may beassociated with an application with a low latency requirement, such asan ultra-reliable low-latency requirement URLLC, for example. A higherfrequency band (e.g., the 5 GHz or 6 GHz band) may be generallypreferred for low-latency communications, while one or more lowerfrequency bands may be used as auxiliary bands for backup communication.

While embodiments herein generally refer to selective transmission overfirst and second frequency bands, other embodiments may apply similartechniques to selective transmission over first and second channels onthe same or different frequency bands. In other words, while someembodiments are referent to a “first frequency band” and a “secondfrequency band” other embodiments may operate similarly, but referent toa “first channel” and a “second channel”, where the first and secondchannels may operate within the same or different frequency bands.

In some embodiments, the remote device may be awake on both the residentand alternative bands (e.g., the 5 GHz and the 2.4 GHz bands). In someembodiments, both the UE and the remote device may be capable ofsimultaneous dual-band (or potentially tri-band) radio communications.In other words, both the UE and the remote device may be simultaneouslyavailable on both of the first and second frequency bands. In someembodiments, may device may be configured to perform channel hoppingonto the same channels in their respective bands. For example, thetraffic pattern of a low latency application associated withcommunications between the UE and the remote device may be known to boththe transmitter and receiver, such that the periodicity at which thepackets are to be transmitted and received may be known. In someembodiments, both the UE and the remote device may be synchronized by apeer-to-peer protocol such as Wi-Fi Aware™ or another protocol.

In various embodiments, some of the elements of the methods shown may beperformed concurrently, in a different order than shown, may besubstituted for by other method elements, or may be omitted. Additionalmethod elements may also be performed as desired. As shown, the methodmay operate as follows.

At 502, communications are periodically transmitted to a remote deviceover a first frequency band on the WLAN using a first radio.

At 504, a frame associated with the first frequency band is determinedto have been reserved for longer than a threshold duration of time. Insome embodiments, determining that the frame associated with the firstfrequency band has been reserved for longer than the threshold durationof time includes monitoring a header field of a broadcast message from asecond remote device (e.g., one not involved in the communication ofFIG. 5 ), wherein the header field includes a network allocation vector(NAV) reservation.

In some embodiments, the equation shown below may be used to determinewhether to switch transmissions to the second frequency band, where x isacceptable packet delay for the low latency communication (e.g., x maybe the number of milliseconds for which a low latency communicationbetween the UE and the remote device may be delayed without adverselyaffecting the communication, such as by causing a delayed receivedpacket to be dropped), n is the remaining time that the frame isreserved, p is a packet duration based on Tx packet size, Tx rate and/orBlockAck time, and g is a guard time.t=x−(n+p+g),  (1)

In Equation 1, the UE may determine to switch to transmit communicationsusing the second radio over the second frequency band if t is negative,and may continue transmitting communications using the first radio overthe first frequency band if t is positive, in some embodiments.

If 2.4 GHz NAV expiry is less than t then move the packets from 5 GHzradio to 2.4 GHz radio and schedule the packet for transmission on 2.4GHz.

At 506, based at least in part on determining that the frame associatedwith the first frequency band has been reserved for longer than thethreshold duration of time, communications are periodically transmittedto the remote device on the WLAN using the second radio until aremaining duration of time that the frame is reserved is less than thethreshold duration of time.

In some embodiments, the methods steps of FIG. 5 may be performed onlywhen the transmitter and receiver experience a mutual signal strengththat is greater than a threshold level such as −70 dB or another signalstrength threshold. For example, it may be determined whether a signalstrength of transmissions received from the remote device is above asignal strength threshold. In these embodiments, said periodicallytransmitting communications to the remote device on the WLAN using thesecond radio may be performed further based at least in part determiningthat the signal strength of transmissions received from the remotedevice is above the signal strength threshold.

In some embodiments, subsequent to determining that the frame associatedwith the first frequency band has been reserved for longer than thethreshold duration of time, it may be determined that the secondfrequency band has been reserved for transmitting BlueTooth™communications. For example, in some embodiments the 2.4 GHz band may beutilized for both BlueTooth™ communications and WLAN communications, anda low latency WLAN communication may generally have a higher prioritythan a BlueTooth™ communication. In these embodiments, currenttransmissions of BlueTooth™ communications over the second frequencyband may be aborted and/or future transmissions of BlueTooth™communications over the second frequency band may be suspended while theUE is periodically transmitting communications to the remote device onthe WLAN using the second radio.

In some embodiments, it may be determined that a number of suspendedtransmissions of BlueTooth™ communications exceeds a predeterminedthreshold. In these embodiments, based at least in part on determiningthat the number of suspended transmissions of BlueTooth™ communicationsexceeds the predetermined threshold, transmission of BlueTooth™communications over the second frequency band may be resumed, and/orperiodically transmitting communications to the remote device on theWLAN using the first radio may be resumed.

In some embodiments, subsequent to determining at step 504 that theframe associated with the first frequency band has been reserved forlonger than the threshold duration of time, the transmitting UE maydetermine whether a frame of the second frequency band is also currentlyreserved. If the frame of the second frequency band is also currentlyreserved, the transmitting UE may determine which frequency band has ashorter duration of remaining reservation, and may use the frequencyband with a shorter remaining reservation for performing transmissionsto the remote device. If the second frequency band is not currentlyreserved, the UE may determine to use the second frequency band.

In some embodiments, based on a determination that the remainingduration of time that the frame is reserved is less than the thresholdduration of time, periodically transmitting communications to the remotedevice on the WLAN may be resumed using the first radio.

In some embodiments, the remote device may perform a similardetermination as the transmitter. For example, the remote device maydetermine that the frame of the first frequency band has been reservedfor longer than the threshold duration of time, and the remote devicemay anticipate the switch to the second frequency band. Alternatively oradditionally, the remote device may be aware of the scheduledperiodicity of transmissions from the transmitting UE, and may detect anabsence of reception over the first frequency band within a time window,and may determine that the UE intends to switch to transmissions overthe second frequency band.

Regardless of how the remote device determines that the transmitting UEintends to switch to the second frequency band for transmission, oncedetermined, the remote device may abort any ongoing BlueTooth™ or otheractivity on the second frequency band in anticipation of the packettransmission from the UE device. In some embodiments, the remote devicemay suspend any ongoing BlueTooth™ communications and delay any upcomingBlueTooth™ communications until either the packet reception with the UEdevice over the second frequency band is finished or a timeout occursfor waiting for the packet from the transmitting UE device over thesecond frequency band.

In some embodiments, the number of overrides over BlueTooth™ (orcommunications over the second frequency band on other RATs) may belimited to a given time period, beyond which the WLAN prioritizationrequest may be rejected and BlueTooth™ communications may be resumedover the second frequency band. In some embodiments, the remote devicemay be preconfigured with a maximum duration of time to receive packetsover the second frequency band before switching back to the firstfrequency band.

In some embodiments, the second frequency band may be unavailablebecause of another NAV reservation on that band, because of a WLANprioritization request rejection, or because the UE does not supportsimultaneous band operation. In these embodiments, the transmitting UEmay move the outgoing packets to a secondary pre-negotiated channel onthe first frequency band in an ad-hoc manner for transmission. Forexample, in some embodiments the UE device supports simultaneoustransmission and/or reception on multiple bands, and the UE may operateon two channels at the same time, e.g., a primary channel 149 on the 5GHz band and a secondary channel 1 on the 2.4 GHz. These two channelsmay be pre-negotiated and the receiver may continually sense forreceived packets on both channels at the same time. Accordingly, thetransmitting UE may transition between bands and/or channels in anad-hoc manner.

While the method steps described in reference to FIG. 5 refer to a“transmitting UE” that is performing transmissions to a “remote device”that is receiving the transmissions, it is within the scope of thepresent disclosure that communications between two WLAN-capable devicesmay be bi-directional, such that a pair of devices switch between beinga transmitter and receiver. In these embodiments, the described methodsmay alternatively be performed by either of the two communicatingdevices, as desired.

Mode 2: Collaborative Band Selection

Mode 2 operation may include a collaborative approach to S-Txtransmissions, according to some embodiments. For Mode 2 operation, theRx device may be assumed to be awake on both the resident andalternative bands (e.g., the 5 GHz and the 2.4 GHz bands).

For step 402, the Tx device and the Rx device may exchange packets toset up the band selection operation. In some embodiments, the Tx deviceand the Rx device may exchange a traffic flow identifier (TID) which mayallow the RX device to prepare the data path processing ahead of time.The block ACK session for the specified TID may be shared between theresident and alternative bands. The Tx device and the Rx device mayfurther exchange a packet switch condition that defines a latencythreshold. For example, the packet switch condition may define a latencythreshold beyond which the Tx may switch to another band. The Tx deviceand the Rx device may further exchange an order of the band(s) to use.For example, the Tx device and the Rx device may negotiate 5 Ghz as theresident band to use primarily, the 6 Ghz band as a first alternativeband, and the 2.4 Ghz band as a second alternative band to use (e.g., ifboth the 5 GHz and 6 Ghz bands are congested or otherwise unavailable).The Tx device and the Rx device may further exchange a band switch delaythat specifies the time at which the Tx device and the Rx device switchto another band. The Tx device and the Rx device may further exchangeband switching tentativeness that specifies whether the alternative bandis used tentatively or whether the two devices may stay on the currentlyutilized band until the next switch trigger. In other words, the bandswitching tentativeness exchanged between the two devices may specifywhether the alternative band is to be used for some predetermined amountof time, or whether the alternative band is to be used indefinitelyuntil the occurrence of a switch trigger that triggers resumption ofcommunications over the resident band.

For step 404, when the packet switch condition is triggered, the Txdevice may switch to the next band agreed in step 402.

For step 406, after the Tx device switches to the next band, it mayexchange an RTS/CTS to confirm that both the Tx device and the Rx deviceare on the same band.

For step 408, the packet transmission may be performed on thealternative band.

For step 410, after the packet transmission, the Tx device may switchback to the resident band, or alternatively it may stay on the currentband based on band switching tentativeness, as described above.

Mode 3: Non-Scheduled Power-Save Selective Tx Mode

Mode 3 operation may implement non-scheduled S-Tx operation, accordingto some embodiments. For mode 3 operation, the radio operating on analternative band may not be awake 100% of time. For example, the Txdevice and/or the Rx device may be configured to switch betweentransmission and/or reception over each of two or more bands, but maynot have the capability of transmitting/receiving over multiple bandssimultaneously. In these embodiments, at step 406, the Tx device maysend an out-of-band mechanism to wake up the radio of the Rx device onthe alternative band. In some embodiments, the out-of-band mechanism maybe a BlueTooth™™ Low Energy (BLE) packet or another type of wake-upradio mechanism.

Mode 4: Scheduled Power-Save Selective Tx Mode

For Mode 4 operation, the radios of the Tx device and/or the Rx devicemay operate according to a duty-cycle based on a setup procedureimplemented between the Tx device and the Rx device. The duty cycle maybe utilized to save power, as the transmitter/receiver may enter a lowpower mode in between active portions of the duty cycle.

For steps 402-404, as illustrated in FIG. 6 , the Tx device and the Rxdevice may negotiate the wake/sleep cycle through target wakeup time(TWT) messages for the radios on the bands to be used. For example, theTx device and the Rx device may exchange signaling to setup a TWTschedule, whereby transmissions from the Tx device to the Rx deviceexclusively occur during active periods of the TWT schedule. In someembodiments, the TWTs may be grouped into TWT groups, whereby a singlegroup TWT is set up for multiple radios. In some embodiments, the timedifference between TWT service periods within a TWT group may beconfigured to be larger than the band switch delay. For example, asubsequent TWT of the TWT schedule may be set to occur a period of timeafter completion of a previous TWT that is greater than the delayincurred in switching from the first frequency band to the secondfrequency band, as illustrated in FIG. 6 . In some embodiments, theactive durations of the configured duty cycle may be set so as to notoverlap with the band switch procedure. In some embodiments, both the Txand Rx devices may switch between bands according to the TWT scheduleand may not sleep outside of the TWT service periods.

For step 406, if a packet is unable to be transmitted in the residentband in TWT 1, the TX device may switch to the next TWT service periodon a different band and transmit there, if it succeeds in the mediumcontention with other devices. After packet transmission, the TX devicemay switch back to the resident band in the next TWT group time window.In these embodiments, the TWT service periods within a TWT may serve asa backup transmission time, in case the packet is unable to betransmitted in a previous TWT service period in the same TWT group.Advantageously, the TWT setup may allow the multiple radios to be awakeonly at particular times, thus saving power without the need forimplementing an out-of-band mechanism.

Mode 5: Single-Radio Selective Tx Mode

For Mode 5 operation, the Tx and/or Rx device may have a single radiowhereby they are not be capable of concurrently operating on multiplelinks, but are configured to alternate between operation on differentbands. In these embodiments, the Tx and Rx devices may be synchronizedin time through beacons or another synchronization protocol such as802.1AS.

For step 404, the Tx and Rx devices may exchange additional parameters,including one or more of: a beginning of the service interval; aninterval between service intervals; a first time-out value whereby, ifthe Rx device does not receive any transmissions from the Tx device forthe first time-out value on the resident band, it switches from theresident channel to the alternative channel; and/or a second time-outvalue whereby, if the Rx device does not receive any transmissions fromthe Tx device over the alternative band after switching to thealternative band, it switches back to the resident band. An exampleimplementation of the first and second time-out values and theestablishment of a service interval is illustrated in FIG. 7 , accordingto some embodiments. For example, FIG. 7 illustrates how, subsequent tobeginning a service interval, the Rx device waits to receive atransmission over band 1 for a duration of time equal to a first timeoutvalue (TimeOut1). If the Rx device does not receive a transmission fromthe Tx device over band 1 before the first timeout value expires, itwill switch to monitoring for transmissions on band 2, and initiate asecond timeout value timer (TimeOut2) after waiting for a duration equalto the switch delay. Finally, if no transmission is received over band 2after expiration of the second timeout value, at the expiration of theservice interval, the Rx device may resume monitoring for messages overband 1 and reset the first timeout value timer.

Furthermore, in some embodiments the TWT may be modified to indicatethat the TWT 1 service period duration is re-defined as the firsttime-out value, and the TWT 2 service period duration is re-defined asthe second time-out value. Alternatively, in some embodiments a newinformation element may be defined to carry the four parameters:beginning of service interval, interval of service interval, the firsttime-out value, and the second time-out value.

Implementation Details for the 802.11 Standard Protocol

The following paragraphs describe specific implementation details forimplementing embodiments described herein within the 802.11 (e.g.,802.11be) Standard Protocol. The following paragraphs are intended toillustrate a specific example of some embodiments, and is not intendedto be limiting to the scope of the disclosure as a whole, which may beapplicable to a variety of WLAN standards and technologies.

To accommodate operation of Modes 1-5 described above within the802.11be Standard Protocol, one or more of the following signalingelements may be defined. The additional signaling elements may beincluded in the reserved bit field of the protocol messages, asillustrated in FIG. 8 , in some embodiments.

1. Selective Multi-link capability information element (IE), whichincludes a field for the Selective-Tx (S-Tx) mode supported by thetransmitting device, and a field specifying the band switch delay forthe device.

2. Selective multi-link setup information element, which includes one ormore of a fields to specify out-of-band wake up latency, whether theresident band is currently in use, whether one or more alternativeband(s) are in use and the order of the band(s) for switching, trafficflow identifier(s) (TID(s)) that specify whether the device is allowedto use the selective multi-link switch scheme, and/or the tentativenessof the band switch (i.e., whether the switch will persist—permanentafter the current packet transmission).

In some embodiments, the TWT information element may be modifieddepending on the mode employed, according to various embodiments. Forexample, for Mode 4 operation, the TWT IE may include an indication thatthe TWT is for a group TWT using one of the reserved bits in TWT IEControl field. If this bit is set, then the TWT parameters may beredefined to indicate that the TWT parameters in the TWT IE indicate theTWT on the resident band. For Mode 4 operation, the TWT IE may furtherspecify that the TWT on the alternate band(s) are separated in time by aband switch delay.

For Mode 5 operation, the TWT IE may include an indication that the TWTis for Mode 5 operation using reserved bits in TWT IE Control field. Ifthis bit is set, the TWT parameters may be redefined to indicate thatthe TWT service period duration indicates a timeout value to switch tothe next band. Alternatively, for Mode 5 operation, a new IE may bedefined as an action frame to carry the following four parameters:beginning of service interval, interval of service interval, firsttime-out value, and second time-out value.

FIG. 9—Late Packets in Low Latency Traffic Transmissions

FIG. 9 is a schematic diagram illustrating a situation where latepackets arrive during a low-latency traffic transmission. In someembodiments, large NAV reservations and/or a busy transmission mediummay delay the transmission of packets. Transmission delays beyond agiven time window may cause packets to arrive late, and late packets maybe dropped by an application with strict latency requirements.

FIG. 10—Late Packet Mitigation

FIG. 10 is a schematic diagram illustrating a method for mitigating latepacket transmissions during a low-latency traffic transmission,according to some embodiments. In the illustrated diagram, both thetransmitter and receiver are simultaneously available on both 2.4 GHzand 5 GHz frequency bands. Transmission may preferably be performed onthe 5 GHz band (e.g., because of its larger throughput) which may beconsidered primary band/channel. Packets waiting to get medium accessfor transmission for more than a maximum wait time ‘x’ may switch totransmission over a secondary band/channel (e.g., the 2.4 GHz band).

FIG. 11—Flowchart for Late Packet Mitigation

FIG. 11 is a flowchart diagram illustrating a method for mitigating latepacket transmissions, according to some embodiments. The method steps ofFIG. 11 may be performed by a UE such as the UEs 106A-B illustrated inFIGS. 1-2 , for example. In some embodiments, the method steps may beperformed by a processor operably coupled to a first and second radio.In some embodiments, the first radio is configured to perform wirelesscommunications over a first frequency band or channel on a wirelesslocal area network (WLAN), and the second radio is configured to performwireless communications over a second frequency band or channel on theWLAN. In some embodiments, the first frequency band is a 5 GHz frequencyband which serves as a primary or resident band, while the secondfrequency band is a 2.4 GHz frequency band that serves as a secondary orauxiliary band. Alternatively, each of the first and second frequencybands may be any of a 2.4 GHz, 5 GHz, 6 GHz band, or another frequencyband.

In some embodiments, the method steps shown may be performed between aUE and a remote device, which may be another UE of the same or adifferent type. The communications between the two devices may beassociated with an application with a low latency requirement, such asan ultra-reliable low-latency requirement URLLC, for example. A higherfrequency band (e.g., the 5 GHz or 6 GHz band) may be generallypreferred for low-latency communications, while one or more lowerfrequency bands may be used as auxiliary bands for backup communication.

In some embodiments, the remote device may be awake on both the residentand alternative bands (e.g., the 5 GHz and the 2.4 GHz bands). In someembodiments, both the UE and the remote device may be capable ofsimultaneous dual-band (or potentially tri-band) radio communications.In other words, both the UE and the remote device may be simultaneouslyavailable on both of the first and second frequency bands. In someembodiments, may device may be configured to perform channel hoppingonto the same channels in their respective bands. For example, thetraffic pattern of a low latency application associated withcommunications between the UE and the remote device may be known to boththe transmitter and receiver, such that the periodicity at which thepackets are to be transmitted and received may be known. In someembodiments, both the UE and the remote device may be synchronized by apeer-to-peer protocol such as Wi-Fi Aware™ or another protocol.

In various embodiments, some of the elements of the methods shown may beperformed concurrently, in a different order than shown, may besubstituted for by other method elements, or may be omitted. Additionalmethod elements may also be performed as desired. As shown, the methodmay operate as follows.

At 1102, a packet may be queued by a UE for transmission to a remotedevice.

At 1104, the UE may check the 5 GHz NAV reservation to see whenresources will be available for transmitting the packet.

At 1106, the UE determines whether the 5 GHz NAV reservation is longerthan a latency budget of the packet. If the NAV reservation will beavailable in a shorter duration than the latency budget, at 1108 the UEmay wait for available transmission resources and transmit the packet onthe 5 GHz band.

On the other hand, if the 5 GHz NAV reservation is longer than thelatency budget, at 1110 the UE may perform a packet crossover totransmit the packet over the 2.4 GHz band.

At 1112, the UE may check the 2.4 GHz NAV reservation to determine ifand/or when resources will be available for transmitting the packet overthe 2.4 GHz band.

At 1114, the UE determines whether the 2.4 GHz NAV reservation is longerthan the latency budget of the packet. If the 2.4 GHz NAV reservation islonger than the latency budget of the packet, at 1116 the UE drops thepacket.

On the other hand, if the 2.4 GHz NAV reservation is not longer than thelatency budget of the packet, at step 1118 the UE may check whether the2.4 GHz radio of the UE is currently in use for BlueTooth™communications or for another type of communication. At 1120, the UE maydetermine whether WiFi transmissions are currently allowed. If not(e.g., because the 2.4 GHz radio is currently in use for BlueTooth™),the UE drops the packet at step 1116. On the other hand, if WiFitransmissions are currently allowed over 2.4 GHz, at step 1122 the UEtransmits the packet over the 2.4 GHz frequency band.

It is well understood that the use of personally identifiableinformation should follow privacy policies and practices that aregenerally recognized as meeting or exceeding industry or governmentalrequirements for maintaining the privacy of users. In particular,personally identifiable information data should be managed and handledso as to minimize risks of unintentional or unauthorized access or use,and the nature of authorized use should be clearly indicated to users.

In addition to the above-described exemplary embodiments, furtherembodiments of the present disclosure may be realized in any of variousforms. For example, some embodiments may be realized as acomputer-implemented method, a computer-readable memory medium, or acomputer system. Other embodiments may be realized using one or morecustom-designed hardware devices such as ASICs. Still other embodimentsmay be realized using one or more programmable hardware elements such asFPGAs.

In some embodiments, a non-transitory computer-readable memory mediummay be configured so that it stores program instructions and/or data,where the program instructions, if executed by a computer system, causethe computer system to perform a method, e.g., any of the methodembodiments described herein, or, any combination of the methodembodiments described herein, or, any subset of any of the methodembodiments described herein, or, any combination of such subsets.

In some embodiments, a device (e.g., a UE 106 or 107) may be configuredto include a processor (or a set of processors) and a memory medium,where the memory medium stores program instructions, where the processoris configured to read and execute the program instructions from thememory medium, where the program instructions are executable toimplement any of the various method embodiments described herein (or,any combination of the method embodiments described herein, or, anysubset of any of the method embodiments described herein, or, anycombination of such subsets). The device may be realized in any ofvarious forms.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

What is claimed is:
 1. A user equipment (UE) device, comprising: a firstradio configured to perform wireless communications over a firstfrequency band on a wireless local area network (WLAN); a second radioconfigured to perform wireless communications over a second frequencyband on the WLAN; and a processor operably coupled to the first andsecond radios, wherein the processor is configured to cause the UEdevice to: periodically transmit data to a second device on the WLANover the first frequency band; determine that a frame associated withthe first frequency band has been reserved for longer than a thresholdduration of time; and based at least in part on determining that theframe associated with the first frequency band has been reserved forlonger than the threshold duration of time, transmit communications tothe second device over the second frequency band until a remainingduration of time for which the frame is reserved is less than thethreshold duration of time.
 2. The UE device of claim 1, wherein the UEdevice is further configured to: based at least in part on adetermination that the remaining duration of time for which the frame isreserved is less than the threshold duration of time, resumeperiodically transmitting communications to the second device on theWLAN over the first frequency band.
 3. The UE device of claim 1, whereinthe UE device is further configured to: determine that a signal strengthof transmissions received from the second device satisfies a signalstrength threshold, and wherein transmitting communications to thesecond device over the second frequency band is performed further basedat least on determining that the signal strength of transmissionsreceived from the second device satisfies the signal strength threshold.4. The UE device of claim 1, wherein the UE device is further configuredto: subsequent to determining that the frame associated with the firstfrequency band has been reserved for longer than the threshold durationof time, determine that the second frequency band has been reserved fortransmitting BLUETOOTH communications; and suspend transmission ofBLUETOOTH communications over the second frequency band whiletransmitting communications to the second device over the secondfrequency band.
 5. The UE device of claim 4, wherein the UE device isfurther configured to: responsive to determining that a number ofsuspended BLUETOOTH transmissions satisfies a predetermined threshold:resume transmission of BLUETOOTH communications over the secondfrequency band; and resume periodically transmitting communications tothe second device on the WLAN over the first frequency band.
 6. The UEdevice of claim 1, wherein the first frequency band comprises a 5 GHzfrequency band and the second frequency band comprises a 2.4 GHzfrequency band.
 7. The UE device of claim 1, wherein determining thatthe frame associated with the first frequency band has been reserved forlonger than the threshold duration of time further comprises: monitoringa header field of a broadcast message from a third device, wherein theheader field comprises a network allocation vector (NAV) reservation. 8.An apparatus, comprising a processor and configured for inclusion withina user equipment (UE) device, wherein the apparatus is configured tocause the UE device to: periodically transmit data to a second device ona wireless local area network (WLAN) over a first frequency band;determine that a frame associated with the first frequency band has beenreserved for longer than a threshold duration of time; and based atleast in part on determining that the frame associated with the firstfrequency band has been reserved for longer than the threshold durationof time, transmit communications to the second device over a secondfrequency band until a remaining duration of time for which the frame isreserved is less than the threshold duration of time.
 9. The apparatusof claim 8, wherein the apparatus is further configured to cause the UEdevice to: based at least on a determination that the remaining durationof time for which the frame is reserved is less than the thresholdduration of time, resume periodically transmitting communications to thesecond device on the WLAN over the first frequency band.
 10. Theapparatus of claim 8, wherein the apparatus is further configured tocause the UE device to: determine that a signal strength oftransmissions received from the second device satisfies a signalstrength threshold, wherein transmitting communications to the seconddevice over the second frequency band is performed further based atleast on determining that the signal strength of transmissions receivedfrom the second device satisfies the signal strength threshold.
 11. Theapparatus of claim 8, wherein the apparatus is further configured tocause the UE device to: subsequent to determining that the frameassociated with the first frequency band has been reserved for longerthan the threshold duration of time, determine that the second frequencyband has been reserved for transmitting BLUETOOTH communications; andsuspend transmission of BLUETOOTH communications over the secondfrequency band while transmitting communications to the second deviceover the second frequency band.
 12. The apparatus of claim 11, whereinthe apparatus is further configured to cause the UE device to:responsive to determining that a number of suspended BLUETOOTHtransmissions satisfies a predetermined threshold: resume transmissionof BLUETOOTH communications over the second frequency band; and resumeperiodically transmitting communications to the second device on theWLAN over the first frequency band.
 13. The apparatus of claim 8,wherein the first frequency band comprises a 5 GHz frequency band andthe second frequency band comprises a 2.4 GHz frequency band.
 14. Theapparatus of claim 8, wherein determining that the frame associated withthe first frequency band has been reserved for longer than the thresholdduration of time further comprises: monitoring a header field of abroadcast message from a third device, wherein the header fieldcomprises a network allocation vector (NAV) reservation.
 15. A methodfor operating a user equipment (UE) device, the method comprising:periodically transmitting data to a second device on a wireless localarea network (WLAN) using a first radio over a first frequency band;determining that a frame associated with the first frequency band hasbeen reserved for longer than a threshold duration of time; and based atleast in part on determining that the frame associated with the firstfrequency band has been reserved for longer than the threshold durationof time, transmitting communications to the second device on the WLANusing a second radio over a second frequency band until a remainingduration of time for which the frame is reserved is less than thethreshold duration of time.
 16. The method of claim 15, furthercomprising: based at least in part on a determination that the remainingduration of time for which the frame is reserved is less than thethreshold duration of time, resuming periodically transmittingcommunications to the second device on the WLAN over the first frequencyband.
 17. The method of claim 15, further comprising: determining that asignal strength of transmissions received from the second devicesatisfies a signal strength threshold, and wherein transmittingcommunications to the second device over the second frequency band isperformed further based at least on determining that the signal strengthof transmissions received from the second device satisfies the signalstrength threshold.
 18. The method of claim 17, further comprising:subsequent to determining that the frame associated with the firstfrequency band has been reserved for longer than the threshold durationof time, determining that the second frequency band has been reservedfor transmitting BLUETOOTH communications; and suspending transmissionof BLUETOOTH communications over the second frequency band whiletransmitting communications to the second device over the secondfrequency band.
 19. The method of claim 15, further comprising:responsive to determining that a number of suspended BLUETOOTHtransmissions satisfies a predetermined threshold: resuming transmissionof BLUETOOTH communications over the second frequency band; and resumingperiodically transmitting communications to the second device on theWLAN over the first frequency band.
 20. The method of claim 15, whereindetermining that the frame associated with the first frequency band hasbeen reserved for longer than the threshold duration of time furthercomprises: monitoring a header field of a broadcast message from a thirddevice, wherein the header field comprises a network allocation vector(NAV) reservation.